1. Field of the Invention
This invention relates to a manufacturing method of a double chamber aerosol container used where contents, such as hair care products, cosmetics, antiperspirant-deodorants, other human body treatment products, insecticides, coating materials, cleaners, and other products for household, industrial materials, automobile goods, medicines, foods, and so on, are filled in an inner sack and where a propellant is filled in an outer container below a mountain cup or container cap.
2. Description of Related Art
Containers in which an inner sack filled with contents is mounted within an outer container and its volume is reducible according to reduction of the contents, have been known previously. In a double-chamber aerosol container, any direct contact between the propellant and the aerosol contents is not favorable.
In such a conventional double chamber aerosol container, the inner sack is attached inside the aerosol container where an edge of an orifice of the inner sack is engaged with a bead portion of the aerosol container and where the lower end of the inner sack is in contact with the bottom of the aerosol container. Contents only, without any propellant, are filled within the inner sack thus mounted.
After those contents are filled, the container cap is fitted inside the inner sack. After an upper opening of the inner sack is disposed at a space between the container cap and the bead portion of the aerosol container, the inner sack and the container cap are lifted upward to form a filling gap for the propellant between the outer periphery of the opening of the inner sack and the bead portion of the aerosol container, and thereby the propellant is filled within the aerosol container via the filling gap.
With this conventional method, however, the exterior is in air communication with the inside of the inner sack, because the contents are placed in the inner sack where the inner sack before the container cap is fitted is mounted within the container. If the contents are filled in such a circumstance, the contents may be spilt out when the container cap is fitted where the contents are filled up closely to the opening of the inner sack. On the other hand, if the contents are filled in a smaller amount, air may remain in the inner sack, and as a result, the contents may be oxidized or deteriorated.
Where the contents are agent type using an isopentane in a gel form or the like, the contents may be deteriorated due to contacts with the open air, or the isopentane may evaporate and generate bubbles where the temperature of the isopentane increases due to contacts with the open air, and those raise problems during such filling work. In case the open air contacts with the contents, such contacts are not favorable for medicines, cosmetics, foods, and so on for which prevention of contamination is strongly demanded.
The inner sack is in a state that the bottom of the inner sack is in contact with the inner surface of the bottom wall of the aerosol container to endure the weight of the contents when the contents are filled where the inner sack is mounted within the aerosol container. The bottom end of the inner sack thus contacts with the bottom of the aerosol container, so that the inner sack is advantageously stably disposed within the aerosol container in opposing to the weight of the contents.
In case the inner sack extends longer than the standard size due to manufacturing deviations of the inner sack or extensions of the material, however, the bead portion of the aerosol container is not properly in contact with the outer peripheral surface of the inner sack, thereby frequently rendering the inner sack inclined or projected upward. In such a case, sealing may become inadequate during clinching between the container cap and the bead portion at the final process. In case the inner sack is formed shorter than the standard size, the inner sack may accidentally drop in the aerosol container, and disadvantageous problems for the manufacturing process may happen frequently.